By-pass selector circuit



Oct. 1 192 7 E. JACOBSEN BYPASS SELECTOR CIRCUIT- I etl Filed May 1926 I3 Sheets-She /7V/7/0/. [/m/ Jaaafise/Z Y Oct. 1111927.

. E. JACOBSEN BY PASS SELECTOR CIRCUIT 3 I Sheeis-Sheet 2 "iled May 8;192

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Filed May a. 1 926 5 Sheets-Shae; 5

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BE Q E 1 E a I 0 I Q C 1 g-l-H l V R E l H Patented Oct. 11, 1927.

UNIT-E" SYS- OFFICE.

EMIL JACOBSEN. F PLANDOME, NEW! YORK, ASSIGNGB TO AMERICAN TELEPHONE ANDTELEGRAPH COMPANY; A CORPORATION OF NEW YORK.

BY PASS SELECTOR CIRCUIT.

Application filed May'8, 1926. Serial No. 107,755.

lect a main office trunk and selector on all.

calls whether to a main office or a satellite office. lVhen the call'was for a satellite ofan extra digit was dialed vhicbi caused therepeater to release the main ofiice trunk and complete the call over alocal trunk.

eater after releasing the main oflice trunk hunted for an idle trunk toa tribu-,

tary office with the same set of brushes which were originally used inconnecting to the main office trunk. I

in this invention the same end is attained with the use of a repeaterhaving two sets of banks and brushes trunks to the main office beingconnected to one set and trunks to a local oliice being connected to theother.

I lso it is not necessary to dial an extra 't in ord r to complete acall to a local the main oflice trunk and switch to the .5 set ofbrushes which are connected to the local otlice, by external. means. ad-

35 vantages will be pointed out in the ioilowinc" description andclaims.

he system disclosing the invention in one of its narrow aspects consistsof a calling line in a satellite or local oilice, a by-pass se- 40lector and repeater circuit, a trunk to a main office, a main otliceselector and a trunk from the by-pass selector to a local selector in alocal or satellite office. The bypass selector is the principal featureo this invention bein used for by-passing a call from a. local suscriberto a local subscriber without the necessity of going through a mainoffice. WVhen a call is initiated whether for a local or main oitlcesubscriber, it is routed to a main office selector. Certain levels ofthis selector have battery and ground connected thereto and these levelsare reached by the dialing of certain numbers which are assigned tolocal office subscribers.

' The battery and ground connected tothese riber as the repeater iscaused to relevels operates a polarized relay in the bypass selectorwhich causes the release of the main office second selector switchandinitiates the selection of a'trunk to aisecond selector in a tributaryofiice- Thisleaves the main office selector'free for useby other bypassselectors. V

The number of digits dialed is the same for a. call to a main oflice asit is for a call to a local otlice, that is, if it takes three digitstocomplete a connection to a subscribers station in a main oilice, it willbe necessary to dial three digits to reach the subscriber in a localoilice'. A. more clear. conception may be obtained of the objectsandoperation of this invention. frointhe following descrip tion inwhich: J

Figure 1 shows the bypass selector S with two sets of brushes, the upperset of which are'connected to a selector in the main oflice and thelower connected to a selector in a tributary office.

Fig. 2 shows a second selector in a main office, the banksof which areshown connected. to a subscribers station in the 'main office and otherbanks to which battery and ground are connected for controlling theselectors. The brushes are shown in their normal position.

Fig. 3 shows a selector in a local office. v Fig. 4 is a diagrammaticrepresentation of the system. line, B the by-pass selector, B the mainoffice selector and C a subscribers line at the main oiiice. E istheselector in the local oflice and the line from R to E desigswitch 102selects the bypass-selector. S in a manner well known in the art. Acircuit is closed for relay 107 from ground through its right winding,right back contact of relay 108, outer left back contact of relay 106,brush and terminal 103 of line switch102, through the subscribers loop101, line switch 102, brush and terminal 104, inner left back contact ofrelay 106, left back contact of relay 108 to battery through the windingof relay 107. The operation of relay 107 closes the bridge formed by theright winding of relay 11 i across. the conductors to the arcs 120 and130. The operation of relay 107 also operates relay 109 overan obviouscir- A is a calling subscribers cuit. The operation of relay 109connects ground from its outer left front contact to terminal 105holding line switch 102 operated. Relay 109 also prepares in part acircuit for stepping magnet 116 and test re- My 111. If the selectorbrushes 120, 130

' and 140 are in contact with a busy trunk such as 205 to the mainoflice, ground will be connected to brush 140 thereby closing a circuitfor magnet 116 from said ground, inner-right back contact of relay 111,inner left front contact of relay 109, outer left back contact of relay.113 to battery through the interrupter contact and winding of magnet116. A parallel circuit is also closed from ground on the outer rightback contact of relay 113, outer right front contact of relay 109,winding of relay 111, middle left back contact of relay 113 to batterythrough the magnet 116. The ground on are 140 acts as a shunt to'thewinding of relay 111 which does not operate, but magnet 116 operates andsteps brushes 120, 130 and 140 until an idle trunk is found, at whichtime relay 111 operates in a series circuit through the winding ofmagnet 116. Magnet 116, however, does not operate as tl e resistance ofrelay 111 is too high. The operation of relay 111 closes the talkingconductors through to arcs 120 and 130 and connects ground to the brushof arc 140 thereby making the trunk test busy to all other selectors.The operation of relay 109 also closes an obvious circuit from ground onthe outer right back cont-act of relay 113 through the left winding ofrelay 114 thereby preparing it as a polarized relay. This relay,however, does not operate at this time over its left winding.

Subscriber 101 now operates dial 121 whichopens the circuit throughrelay 107. The release of relay'107 does not release relay 109 as relay109 is a slow-to-release type relay which holds up thereby closing acircuit from ground on the rightback contact of relay 107, inner rightfront contact of relay 109 to battery through the winding of relay 110.Relay 110 is also slow-to-release and does not release at any timeduring dialing. The operating of relay 110 closes a circuit from groundon the outer right back contact of relay 113, outer right front contactof relay 109, right front contact of relay 110, inner back contact ofrelay 114 to battery through the winding of relay 115. As the dial 121returns to normal, relay 107 follows the dial impulses and opens andcloses the circuit from battery through the left winding of relay 222,inner right back contact of relay'213, conductor 139 of trunk 205, brushand are 130, middle right front contact of relay 111, left front contactof relay 110, left front contact of relay 107, outer right front contactof relay 111, brush and arc 120, conductor 129 of trunk 205, outer leftback contact of relay 213 to ground on following release of relay 222now closes a circuit from ground on the inner left back contact of relay213, back contact of relay 222, left front contact of relay 221, Windingof relay 220 to battery through the vertical magnet 219. During thefollowing impulses relays 220 and 221 remain operated as they are of aslow-to-release type. The operation of vertical magnet 219 causesbrushes 210, 211 and 212 to be moved upward to the desired level whichcontains terminals 207, 208 and 209. When these brushes leave theirnormal position the off normal springs 224 are closed to enable theclosing in part of a circuit for relay 216 from ground on the rightfront contact of relay 221, front contact of relay 220, upper contact ofoff normal contact springs 224, to battery through the winding of relay216. Relay 216 locks over a circuit from ground on the inner left backcontact of relay 213, outer front contact of relay 216, back contact ofmagnet 215, upper contact of off normal contact springs 224 to batterythrough the winding of relay 216.

hen the dial has returned to normal af ter dialing the first digit,relay 220 releases and a circuit is closed as follows for the rotarystepping magnet 215: battery, through the winding of said magnet, innercontact of relay 216, normal contact of relay 220 to ground at the rightcontact of relay 221. The magnet 215 advances the brushes 210, 211 and212 to the first set of terminals. Magnet 215 also opens the circuit ofrelay 216, releasing this relay and the relay in turn opens theoperating circuit of magnet 215 permitting it to release. If the firstset of terminals engaged by the brushes is busy the relay 216 againoperates in a circuit from battery through its winding, contacts 224,contact of magnet 215, right back contact of relay 213, brush 212 to thegrounded busy terminal. Relay 216 operates closing the circuit for themagnet 215 which advances the brushes to the next set of terminals. Thisoperation will be repeated until an idle trunk is found. A circuit isclosed during the operation of magnet 215 from ground on the right frontcontact of relay 221, upper normal contact of the eleventh rotaryposition off normal contact spring 206, winding of relay 213, backcontact of magnet 215, upperalternate contact of ofi normal contactspring 224 to battery through the winding of relay 216 in parallel withone from busy ground on brush 212 through the outer right back contactof relay 213 and thence over the same circuit through'the winding'ofrelay 213. While the brush 212 is resting on a busy terminal relay 213is shunted but as soon as an idle terminal is found this shunt isremoved and relay 213 operates and connects conductors 129, 139 and 149through to brushes 210, 211 and 212. Due to the resistanceof the circuitrelay 216 does not op erate in series with relay 213. 3 it will beassumed that brushes 210, 211 and 212 are resting on terminals 207, 208and 209 from which the connection would be completed to station 201through the third selector and connectorin a manner wellknown to theart.

As this system has to do with the switching from a main office selectorto a local of ice sel ctor, an explanation of the wiring of arcs 250,251 and 252 will be necessary. Certain levels on the switch over i whichbrushes 210, 211 and 212 move are wired direct to lines in the mainotfice such as line If however, the call is for a line such as 301 in alocal oiiice, certain levels such as those containing terminals 203 and204, corresponding to the first digit of the subscrihcrs number havebattery and ground connected thereto for giving a battery reversal tothe bypass selector. When such a call is made, the operation of the mainotlice selector switch will be difierent. After the first digit isdialed and the rotary magnet 215 is operated brushes 210, 211and 212 arecaused to hunt. No ground will be found on this bank for brush 212therefore relay 213 will operate as described above and close theconductors 129, 139 and 149 hrough to brushes 210, 211 and 212 which areassumed to be resting on terminals 203 and 204. Battery and ground willbe connected to these terminals and will close a circuit from battery onterminal 203, brush 210, outer left front contact of relay 213,conductor 129, are and brush 120, outer right front contact of relay111, left front contact of relay 107 through the polarized winding ofrelay 114, middle right frontcontact of relay 111, are and brush 130,conductor 139, inner right front contact of relay 213 to ground onterminal 204 through brush 211. Relay 114 operates and opens the circuitthrough relay 115 which is slowto-release and so holds up until acircuithas been closed for operating relay 113 from ground on the outerfront contact ofrelay 114, front contact of relay 115 to battery throughthe winding of relay 113. -Relay 113 operates and locks over an obviouscircuit to ground on the outer left front contact of relay 109. Theoperation of relay 113 closes a circuit from battery through the windingof magnet 116, outer left front contact of relay 113 to ground throughthe winding of relay 106. The operation of relay 113 also opens thecircuits for relays 111 and 114 and allows them torelease.

The release of relay 111 opens the holding circuit for relay 213. Therelease of relay 213 closes a circuit for ground on. its inner left backcontact, back contact of relay 222,

left back contact of relay 221, lower alternet 116 will be operatedthereby stepping.

brushes 150', 160 and 170 until an idle trunk is reached when the shuntaround'relay 106 is removed allowing it to operate. Magnet 116 does notoperate at this time as the resistance of relay 106 is too high. Theoperation of relay 106 disconnects conductors 126 and 136 from terminals103 and 104 and connects conductors 131, 132 and 133 to terminals 103,104 and 105 through the contacts of relay 106. When conductors 126 and136 are disconnected, the circuit of relay 107 is also opened allowingit to release, in turn releasing relays 109 and 110.

Selector S is now in condition for the next digit to be dialed to theselector in the local oflice over leads 169 and 179. A circuit 1s closedfrom ground through the left winding of relay 322, outer right backcontact of relay 313, conductor 17 9, brush and are 17 0, conductor 132,outer left front contact of relay 106, terminal and brush-1030f lineswitch 102 through the subscribers loop, brush and terminal 104, innerleft front contact of relay 106, conductor 131, brush and are 160,conductor 169, innerleft back contact of relay 313 to battery throughthe right winding of relay 322. Relay 322 follows the dial impulses inthe same manner as relay 222 and the operation of the circuit is thesame as that described for the selector in Fig. 2. It will be noted thatthe num bering of the apparatus of Fig. 3 is the same as that of Fig. 2with the exception of the hundreds digit.

After the brushes 310, 311 and 312 ofthe selector switch have been set,on the termi-.

l/Vhen subscriber 301 replaces the receiver on the switchhook, therelease of the switches in Fig. 3 is the same as that described for theselector in Fig. 2 when released by the by-pass selector.

What is claimed is:

1. In a telephone system, a selector hav ng a plurality of banks and asingle operating mechanism, a plurality of trunks, part of said trunksbeing connected to part of said banks, the remainder of said trunksbeing connected to the remainder of said banks, means l'or setting saidswitch to establish a connection through one of said banks, and means insaid selector for automatically releasing said switch andre-establishing said connection through another of said banks.

2. In a telephone system, a selector having a plurality of banks, setsof brushes "for cooperating with said banks, a s ngle operatingmechanism for driving said brushes, a plurality of trunks toa mainoihce, a plurality of trunks to a local o'l'lice, said mainoflice'trunks being connected to part of said banks, said local oliicetrunks being connected to the remainder of said banks and means in saidselector for switching from one group of trunks to tne other.

3. In a telephone system, a repeater having two sets of terminal banksand two sets of brushes cooperating therewith, a trunk to a main officewith a selector con nected thereto, a trunk to a local oi'lice, saidmain oilice trunkbeing connected to terminals in one set of banks, saidlocal office trunk being connected to terminals in the remaining set 01"banks, means in said repeater for causing said repeater to switch fromone trunk to the other, and means in said selector for operating saidfirst means 4;. In a telephone system, a by-pass repeater having twosets of terminal banks, a trunk to a. main otfice with a selectorconnected thereto, a trunk to a local oilice, said main office trunkbeing connected to one set of said banks, said local otfice trunk beingconnected to the other set, said selector having different levels ofterminals in its banks, a source of potential connected to certain ofsaid levels which are assigned to the same designation as that of thelocal trunk, and means in said repeater operated by said source ofpotential for causing said repeater to switch to said local trunk.

5. In a telephone system, a bypass repeater having two sets of terminalbanks, a trunk to a main oflice with a selector connected thereto, atrunk to a local office, said main oflice trunk connected to one set ofsaid banks, said local oflice trunk connected to the other set, means tocause said repeater to connect with said main oifice trunk, said mainoliice selector having different levels of terminals in its banks,sources of potential connected to certain 01" said levels to which areassigned the same designation as the local trunk, and a polarized relayin said repeater operated by said sources for causing said repeater toswitch to said local trunk.

'6. In combinatioma repeater circuit comprising two sets of terminalbanks with separate sets of brushes cooperating therewith, a main oflieetrunk connected to one set of terminal banks, a local oi'lice trunkconnected to the other set of said banks, a polarized relay and meansactuated over said main ollice trunk for operating said polarized relayto cause said repeater to switch from one trunk to the other.

7, In a telephone system, a main exchange and a. local exchange, aselector having a plurality of arcuate banks of contacts, wipers forengaging said contacts, a mechanism for operating all of said Wipers ina step-by-step movement, a group of trunks leading from some of saidbanks to the main exchange, a second group ot' trunks leading from otherof said banks to the local exchange, and means in said selector forswitching from one group of trunks to the other.

In testimony whereof, I have signed my name to this specification this7th day of May 1926.

EhIIL JACOBSEN.

